Patent GB-734607-A (GB)
Title: Improvements in or relating to shell moulding
Inventor: JONES ARTHUR WANSBROUGH
IPC: B22C23/00
Filed: 1952-12-01
Abstract: 734,607. Moulding processes and machines. SHAW PROCESSES, Ltd. Dec. 1, 1953 [Dec 1, 1952], No. 30450/52. Class 83 (1). A method of producing shell moulds comprises mounting a mould plate 15 in a frame or platen 11, heating the plate by means of a heating unit 22 depositing the shell-forming materia thereon from a container 35, curing the shell and ejecting the finished mould, the mould plate being retained in the frame during the whole of the operation and the heating unit and container being brought successively into operative relation, with the frame. The platen 11, is pivotally mounted by trunnions 12 in a machine frame 10 and arranged to turn through 180 degrees by means of a rack 16 on the piston rod. 17 of a compressed air cylinder 18 engaging a pinion 20 on one of the trunnions 1:2,-and the heater 22 is pivotally supported on the frame 10 by means of a pair of parallel links 23, 24 and is movable, by means of a rack 30 on the piston rod 31 of a second compressed air cylinder 32 engaging a pinion 29 on the shaft 26 for the links 23, from a position of rest (Fig. 3) to an operative position in which it covers the platen 11. The container or sandbox 35, for the mixture of sand and uncured resin, is provided with two stub shafts 35a each having fixed to it an arm 35b pivotally connected to one of a pair of arms 36 secured to a shaft 37 journalled in the frame 10 and carrying a further arm 41 coupled to the piston rod 43 of a third compressed air cylinder 44 whose operation thereby moves the sand-box toward or away from the platen, the sand-box being guided during such movement by rollers 47 engaging in channel tracks 46 fixed to the frame 10. When the platen 11 is inverted so that the mould plate 15 faces downwardly and the sand-box has been moved upwardly until its mouth is in contact with the mould plate, alignment between the pivotal mountings 36a of the box and the trun nions 12 is ensured by pins 51 (Fig. 8), fixed to the arms 36 coaxially with the pivotal mountings 36a which enter notches 52 in arms 53 secured to the frame 10. At the same time the pins 51 also enter radial slots in bushes 54 attached to the trunnions 12 so that when the platen is rotated the slots in the bushes 54 and the notches 52 move out of alignment and the box 35 is positively located with respect to the platen. The mould plate is provided with ejector pins 59 (Fig. 12) operable by an ejector plate 61 slidable on rods 62 secured to an internal flange 55 of the platen 11. The ejector plate 61 is retained in its inoperative position by inclined surfaces 67 on a spring-loaded latch 65 engaging corresponding surfaces 68 on a latch plate 71 fixed to the plate 61 which carries adjacent each latch a guide 73 containing a spring-loaded plunger 74 adapted to be engaged by the rim of the sand-box 35 and having at its upper end a roller 75 which, when the plunger moves inwardly, engages a roller 66 to free the latch 65. The supply of compressed air to, and exhaust from, the cylinders 18, 32 and 44 is controlled by valves operated by solenoids controlled by relays each associated with a timing device and the sequence of operations in auto. matic operation is controlled by a bank of cams rotated by a constant speed electric motor. The electric circuit can also be set to allow selective hand control. In a cycle of operations commencing with the parts arranged as in Fig. 3 the heater 22 is moved on to the platen 11 and, after a predetermined time, returned. The platen is then turned through 180 degrees and the sand-box is moved upwardly until its edge contacts the mould plate 15 and it is pivoted coaxially with the platen which is then inverted with the sand-box so that the mould material falls on the plate 15. After sufficient time has elapsed to partially cure the resin, the platen and sand-box are reinverted, and the sand-box is lowered to its inoperative position as in Fig. 3. The heater 22 is again moved on to the platen to complete the curing of the resin and then returned. Finally, the sand-box is moved upwardly to move the ejector plate 61 and eject the finished mould.